Efficient engines or the emperor’s new clothes?

We doubt it has escaped anyone’s notice that the dominant theme in the motor industry over the last decade has been everything ‘green’ – or blue, as manufacturers including VW and Mercedes badge it.

Much has been made of advances in efficiency, reductions in fuel consumption and ever lower numbers for the CO2 headlines. Nobody doubts that these are positive developments.

Large petrol engines fell out of favour with the buying public because of their ‘gas guzzling’ reputation and with company car drivers because of the effect on their tax bill. Diesels had apparently cleaned up their act, thanks to technology like common rail injection and particulate filters. Lighter weight aluminium blocks and modern turbos meant that diesels no longer performed well ‘for a diesel’ – they stood up in their own right. Whether it was the promise of being able to travel long distances between fill-ups or the lure of paying less benefit in kind, sales of diesel models began to outstrip petrols like never before.

However, increasingly strict emissions regulations and a ‘downsizing’ trend are starting to see a drift back towards petrol.

Many manufacturers are focusing efforts on small capacity, high output direct injection turbocharged petrol engines. Ford’s 1.0-litre, three-cylinder motor will find a place under the bonnet of the next generation Mondeo. Only one model generation ago the idea of such a tiny engine in such a big car would have been laughable! It’s likely that we’ll soon also see small three-cylinder units powering cars like the BMW 3- or even 5-series.

So this must all be good news for the environment, then? A move to compact, frugal petrol motors that offer much of the flexibility and economy of diesel but without the drawbacks in terms of harmful pollution. Not necessarily.

A recent study by technical research institute TUV Nord found that modern direct injection petrol engines emit up to 1,000 – that’s one thousand – times more particulate matter than traditional petrol motors, making them potentially even more polluting than diesels. Particulate matter is the type of pollution that can be especially damaging to air quality and consequently public health. Evidence has linked particle pollution to respiratory problems, increased risk of heart attack and low birthweights.

Autogas LPG is already proven to produce significantly lower quantities of harmful pollutants in tailpipe emissions compared to diesel, and its cleaner-burning properties could help to improve the environmental credentials of modern petrol cars. While we continue to encourage drivers to consider converting their existing car to run on LPG, what we’d really like to see is manufacturers supporting the greener fuel and offering new LPG models in their UK showrooms – as they already do for our neighbours in mainland Europe.

Not only can LPG contribute to better air quality; the considerably lower price at the pump means that you could save up to 40 per cent on your fuel bills compared to using unleaded. And that’s a benefit clear for all to see!

The cost of autogas LPG, unleaded and diesel fuels per litre displayed and used throughout this website is the UK average taken from petrolprices.com. Please note that the savings calculator is provided as a guide. Actual cost implications should be discussed with the converter/manufacturer of your specific vehicle.